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Electrical Circuits and Machines Question Paper - Dec 18 - Electronics And Telecomm (Semester 3) - Pune University (PU)
written 6.9 years ago by gravatar for teamques10 teamques10 ★ 70k
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written 6.9 years ago by gravatar for teamques10 teamques10 ★ 70k

Electrical Circuits and Machines - Dec 18

Electronics And Telecomm (Semester 3)

Total marks: 80
Total time: 3 Hours INSTRUCTIONS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.

1.a. State and explain Nortan's Theorem.
(6 marks) 00

1.b. Explain construction and working of Isolation transformer. State its applications.
(7 marks) 00

OR

2.a. A single-phase transformer delivers 10 Amp, 220 V to a resistive load while the primary draws 6 Amp at 0.9 lagging p.f. from 450 V, 50 Hz supply. The turns ratio of transformer is 2. Calculate efficiency and regulation under this condition.
(6 marks) 00

2.b. State and explain superposition theorem.
(7 marks) 00

3.a. Sketch and explain D.C. shunt motor characteristics.
(6 marks) 00

3.b. Sketch and explain working of rotor resistance starter used for three-phase induction motor.
(6 marks) 00

OR

4.a. The rotor, of a 6 pole, 440 V, 50 Hz three-phase induction motor, has a power input of 60 kW. The frequency of rotor emf is 1.5 Hz. Calculate :

  1. Rotor Cu loss
  2. Gross mech. power developed
  3. The rotor resistance per phase if the rotor current/ph is 58 Amp.

(6 marks) 00

4.b. A D.C. shunt motor operating on 220 V supply draws current of 22 Amp runs at 800 rpm. Its armature resistance is 1 ohm and field resistance is 110 $\Omega$ . Calculate the additional resistance to be inserted in series with armature to reduce the speed to 520 rpm keeping load on motor constant.
(6 marks) 00

5.a. Compare Brush less DC motor with conventional DC motor.
(6 marks) 00

5.b. Explain with neat diagram working of Universal motor.
(6 marks) 00

OR

6.a. Explain construction and working of Reluctance motor.
(6 marks) 00

6.b. State applications of :

  1. Universal motor
  2. Reluctance motor
  3. Brushless DC motor.

(6 marks) 00

7.a. Explain with a neat diagram working of DC servomotor.
(7 marks) 00

7.b. Explain with neat diagram operation of single-phase shaded pole induction motor.
(6 marks) 00

OR

8.a. What is stepper motor? State different types of it. State applications of stepper motor.
(7 marks) 00

8.b. State applications of :

  1. DC servomotor
  2. AC servomotor
  3. Shaded pole induction motor.

(6 marks) 00

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